Dispensing apparatus



Jan. 10, 1967 D. A. LUCAS DISPENSING APPARATUS Filed Dec. 28, 1964 EGQEEE INVENTOR DEREK A. LUCAS BY Qvc ATTORNEY United States Patent Oflice 3,2912% Patented Jan. 10, 1967 3,297,210 DISPENSING APPARATUS Derek A. Lucas, Dover, Mass., assignor to Hewlett- Packard Company, Palo Alto, Calif.. a corporation of California Filed Dec. 28, 1964, Ser. No. 421,407 1 Claim. (Cl. 222146) This invention relates to apparatus for dispensing small amounts of fluid accurately and at a preselected temperature and more particularly to apparatus that is useful in blood coagulation testing which agitates particulate matter in the fluid to be dispensed.

It is an object of the present invention to provide dispensing apparatus which is easy to clean and which eliminates the need for check valves.

It is another object of the present invention to provide apparatus for automatically dispensing small volumes of liquid at a selected temperature.

In accordance with the illustrated embodiment of the present invention, a hypodermic-type syringe is actuated by electromechanical means to draw a quantity of liquid to be dispensed from a reservoir. The liquid is heated within the syringe to a selected temperature. The reservoir is then moved toward the inlet tube of the syringe to align the tube within an outlet in the lower wall of the reservoir. This forms a fluid-tight seal between the tube and the outlet, the upper end of which is above the liquid level in the reservoir to prevent liquid from escaping from the reservoir. With the tube and outlet sealed, the syringe is actuated to expel the quantity of heated liquid contained therein through the tube and outlet and into a suitable container.

Other and incidental objects of the present invention will be apparent from a reading of this specification and an inspection of the accompanying drawing which shows a cutaway view of the dispensing apparatus of the present invention.

Referring to the drawing there is shown a hypodermictype syringe 9 including a plunger 11 and an outer barrel 13 which is held in position in frame 15. The entire syringe 9 is readily removable to facilitate cleaning. A heating element 17 in frame receives a suflicient amount of power from heater power source 19 controlled by thermostat 21 to maintain the syringe 9 and surroundings at a selected temperature. End 23 of the tube 25 connected to the syringe is disposed below the surface of the liquid 27 in the reservoir 29.

In operation, actuation of button 26 starts the timer 28 which then actuates solenoid 33. This moves the reservoir 29 downwardly against spring 31 so that the end 23 of tube 25 communicates with the liquid 27 in the reservoir 29. The length of travel of the armature 35 is sufficiently restricted so that it does not complete the magnetic circuit in the solenoid 33. This causes the armature to vibrate at the line frequency, which vibrations are transmited to the reservoir connected to the armature 35 for agitating pariculate matter in the'liquid 27 within the reservoir 29. A short time after the agitation of liquid 27 in reservoir 29 commences, the timer 28 actuates solenoid 37 which causes armature 39 to move longitudinally inwardly into the coil. This motion is transmitted by lever arm 41 on pivot 43 and the rack and pinion apparatus 44 to the plunger 11 of syringe 9 which is thereby moved longitudinally outwardly from the barrel 13. Liquid 27 in reservoir 29 is thus drawn up through tube 25 into the syringe 9 where it is heated to a selected temperature.

Timer 28 then deenergizes solenoid 33. Spring 31 urges the armature 35 and reservoir 29 upwardly to engage the ring gasket 45 at reservoir outlet 47 with the tapered end 23 of tube 25 to form a fluid-tight seal. Timer 28 then deenergizes solenoid 37 to complete the operating cycle. Spring 49 rotates lever arm 41 about pivot 43 which in turn moves the plunger 11 longitudinally inwardly to expel the heated liquid within the syringe 9. The expelled liquid passes through tube 25, the fluid-tight seal at end 23 and out through tube 51 connected to the outlet 47 in the'lower wall of reservoir 29 into a suitable container 52. The end 53 of tube 51 is elevated above the level of liquid 27 in reservoir 29 to prevent escape of the liquid 27 during the time solenoid 33 is energized. The accuracy with which a selected volume of liquid is dispensed is preserved by making the interior volume of the tube 51 over its entire length negligibly small compared with the volume of liquid dispensed in an operating cycle.

I claim:

Fluid dispensing apparatus comprising:

a reservoir for containing a fluid to be dispensed;

a fluid outlet in a lower region of said reservoir having a terminal end remote from the reservoir which is disposed above the level of a fluid to be dispensed contained within said reservoir;

a tube having an end disposed in line with said fluid outlet;

means coupled to at least one of said tube and reservoir for moving said one in a direction toward the other of said tube and reservoir between limits of travel to form a fluid-tight seal betwen the end of said tube and the outlet at one limit of travel and to position said end of the tube away from the outlet at another limit of travel for said end of the tube to communicate with a fluid to be dispensed contained in the reservoir, said means including an electro-mechanical solenoid coupled to said reservoir for moving the reservoir vertically along an axis passing through said end of the tube; and

additional means including a chamber with a plunger therein for altering the volume of said chamber and a heater disposed about said chamber for heating fluid present in said chamber connected to said tube for withdrawing fluid to be dispensed therethrough from said reservoir when the tube and reservoir are disposed near said other limit of travel and dispensing a portion of the withdrawn fluid through said tube and outlet when said tube and reservoir are disposed near said one limit of travel.

References Cited by the Examiner UNITED STATES PATENTS 1,376,088 2/1921 Fowler 222381 X 1,795,236 3/1931 Schupp 222381 X 2,854,170 9/1958 Borgardt et al 222381 X ROBERT B. REEVES, Primary Examiner.

HADD S. LANE, Examiner. 

